Queen execution in a monogynous ant

Workers in many species of social insects are capable of laying unfertilized eggs, which can develop into haploid males. This causes a conflict about male parentage between queens and workers. In a few species, this may result in matricide, i.e., workers kill the colony's queen. Queen killing has so far been observed mainly in multi-queen colonies or in annual species, when the queen's fecundity declines at the end of the reproductive period. Here, we report queen expulsion and matricide in a monogynous, monandrous ant with perennial societies. Workers were seen to aggressively expel both related and unrelated queens from their nest shortly after the end of hibernation. Queen expulsion and matricide led to a significant decrease in the number of workers and brood, but eventually increased the direct fitness of workers through significant male production. Long-term observations revealed a short lifespan of queens, while workers in orphaned colonies survived and produced male offspring over several years.

许多社会性昆虫类群的工蚁均可产下未受精卵（unfertilized eggs），此类卵粒可发育为单倍体雄性（haploid males）。这一现象会引发蚁后与工蚁之间关于雄性父权的冲突。在少数类群中，该冲突甚至可能引发弑王后（matricide）行为，即工蚁杀死种群内的蚁后。迄今为止，弑王后行为主要被记录于多后制蚁群（multi-queen colonies）或一年生昆虫类群中，且多发生于繁殖季末期蚁后繁殖力（fecundity）下降之时。本研究报道了一种单后制（monogynous）、单雄配（monandrous）的多年生社会性蚂蚁中存在的蚁后驱逐（queen expulsion）与弑王后行为。研究人员观察到，在冬眠（hibernation）结束后不久，工蚁会攻击性地将亲缘蚁后与非亲缘蚁后一同驱逐出巢。蚁后驱逐与弑王后行为会导致工蚁与巢内子代（brood）的数量显著下降，但最终通过大量雄性子代的产生，显著提升了工蚁的直接适合度（direct fitness）。长期观测结果显示，该类群蚁后的寿命极短；而失去蚁后的蚁群（orphaned colonies）中，工蚁仍可存活并在数年时间内持续产生雄性子代。